Window bar guard systems have been used for some time in an effort to thwart or discourage breaking and entry into a house or other establishment through a window opening. A telescoping window bar guard system is disclosed in U.S. Pat. No. 3,38,062. The system includes two horizontal members having an extensible portion One side of the grillwork is pivotally connected to the window frame The extensible portion is extended and secured to the other side of the window frame by a lock arrangement In the event of fire or the need to clean the window, the system may be unlocked and swung outwardly. The extensible portion is not secured to the horizontal members so that the extensible portion can be retracted in order to release the bar system. Due to the free telescopic nature of the bars of the window system, prying with a crowbar can weaken the connection of either side of the bar guard system to the window frame to allow illegal entry through the window.
A telescopic bar window system, which entails locking the relative positions of the telescoping bars, is disclosed in U.S. Pat. No. 4,437,265. Lock portions are used on at least two of the telescoping horizontal bar members to prevent relative movement therebetween. The ends of the bars are fastened to the opposite sides of the window frame However, to remove the bar system from the window it is necessary to unlock the telescoped bars. The lock provided, in accordance with this patent, is a friction type lock which can be readily tampered with to release and thereby allow illegal entry to a building through the window.
Fixed bar arrangements for window bar guard systems are disclosed in U.S. Pat. Nos. 2,999,682, 2,222,667, 4,019,281 and 4,358,912. Due to the fixed nature of the bars, various mounting systems are employed to permit outward withdrawal of the bar gratings by complete removal or pivotal action. Pivotal action for the bar systems is further demonstrated in U.S. Pat. No. 3,953,939, where a lower segment of the bar system is pivoted upwardly when released.